Question

How many calories are required to heat 10 ml of water from -5 to 25 0C?

a. 110 cal.
b. 0.48 cal.
c. 300 cal.
d. 2.1 cal.

Answer 1

c. 300 cal

Step-by-step explanation:

To calculate the heat, we use the following equation:

heat = m x Cp x ΔT

Where m is the mass of water, Cp is the specific heat of water (which is 1 cal/g.°C) and ΔT is the change in temperature (calculated as the difference between the final T and the initial T).

We have the volume of water (10 ml) but not the mass. As the density of water is 1 g/ml, the mass of water is:

density = mass/volume ⇒ mass = density x volume = 1 g/ml x 10 ml = 10 g

The change in temperature (ΔT) is:

ΔT= Final T - Initial T = 25°C - (-5°C) = 30°C

Finally, we introduce the data to calculate the heat:

heat = 10 g x 1 cal/g.°C x 30°C = 300 cal

Therefore, the correct option is c. 300 cal